Brewing can be simple, but it takes a lot of knowledge and hard work to make it look simple. This software is amazing because it calculates everything about your beer, from calories to end volume to alcohol %. That alone makes it a lot easier to build and tweak recipes, and that means you end up brewing beer you like more! It also helps you save, share, and print recipes for your brew day. A Nicely formatted recipe is a joy to use compared to a small wrinkled flyer, or a website.
Beersmith is only $20 and it is easily worth multiples of that. Pc & mac, and they even have some smartphone integration for a nominal fee.